Method of producing a cutting tool



Dec. 13, 1966 J. M. DON 3,290,917

METHOD OF PRODUCING A CUTTING TOOL Filed July 24, 1963 ATTORNEYS UnitedStates Patent f 3 290 917 METHOD OF PRODiJCihIG A CUTTING T001. Jules M.Don, Naugatuclr, Conn, assignor to The Stanley Works, New Britain, Conn,a corporation of Connecticut Filed July 24, 1963, Ser. No. 297,249 4Claims. (Cl. 72-333) The present invention relates to cutting andabrading tools of the type made from sheet metal and having a number ofintegral cutting elements formed therein for engagement with theworkpiece. More particularly, it relates to a new and improvedconstruction for such tools, particularly the cutting elements thereof,and the method of making such elements and the tools containing them.

It is an object of the present invention to provide a cutting andabrading tool possessing highly effective cutting elements of strongtooth form and an improved internal metal structure which prolongs thedurability and effectiveness thereofv Another object of this inventionis to provide a new and improved cutting tool of the type in which thecutting elements are integrally joined to the tool 'body through theirroot portion and wherein the cutting ele ments may be provided withoptimum rake, included and clearance angles for the intended purpose ofthe tool while retaining strength, efiiciency and durability.

An additional object of the present invention is to provide a cuttingtool of improved quality by means of a method utilizing standard andsimple manufacturing operations and possessing a high degree ofversatility such that desired variations in tooth dimensions and anglesfor various purposes are possible and may be effected with a minimumtooling.

It is a further object of this invention to provide a method ofproducing cutting and abrading tools which is simple and economical touse and which is effective for mass production of tools of uniform highquality at low costs and wherein the tools produced are of rugged designadapted for long service life in a wide variety of uses.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

The invention accordingly consists in the features of construction,combination of elements and arrangement ofparts which will beexemplified in the construction hereafter set forth, and the scope ofthe application of which will be indicated in the appended claims.

In the drawing:

FIG. 1 is a fragmentary plan view of an embodiment of the tool blade ofthe present invention;

FIGS. 2-5 are enlarged sectional views through a single cutting elementof the tool blade illustrating the sequential stages of its manufacture;and

FIG. 6 is an enlarged view taken along the line 6-6 of FIG. 1.

According to the present invention, the cutting and abrading tool, whichmay take the form of a file, rasp, band or disc, is formed by initiallypunching a plurality of holes in a strip of sheet metal; causing aportion of the metal at the peripheries of the holes to cold-flow underthe action of a pair of dies thereby fashioning the initialconfiguartion of the cutting elements and the included angle desired forthe particular tool; grinding one surface of the cutting elements toform the final cutting edges and tooth dimensions; and finally bendingor forming the cutting edge portions of the cutting elements so as toprovide the final toot-h configuration and rake and clearance angles.The cutting elements thus produced may be then treated to obtain thedesired hardness and finished appearance.

329M917 Patented Dec. 13, 1966 Referring now to the invention in greaterdetail and with respect to the drawing, FIG. 1 shows a portion of afinished cutting tool blade 10 made in accordance with the invention.For convenience and brevity of description, the tool will be describedspecifically in connection with a tool intended for hand operation inthe filing of wood; although it may be produced in other forms and foruse in connection with other materials. For hand operation in connectionwith the filing of wood, the tool will be preferably formed of a pieceof strip steel having a width of the order of 1 /2 to 2 inches and alength of approximately 10 inches or more. The thickness of the stripsteel also may vary in accordance with the intended purpose of the tool.For use in connection with wood, a thickness of the order of .01 to .04inch is generally commercially acceptable; whereas for tools intendedfor use with harder materials, a thicker sheet steel will be used.

The tool blade 10 has edges 12 parallel to the iongitudinal axis of theblade and, as shown in FIG. 1, comprises a series of teeth or cuttingelements 14 arranged in rows inclined at an angle to the blade edge 12,and to the normal cutting direction of the tool which, as viewed in FIG.1, is from right to left. Each tooth or outing element 14 is preceded byan aperture or clearance hole 16, and the teeth 14 are in staggeredrelationship. The form of each of the cutting teeth 14 is shown indetail in FIGS. 5 and 6 of the drawing, and the method of forming theteeth is exemplified by the illustrations of FIGS. 2-5 of the drawing.

As illustrated in FIG. 2 of the drawing, the strip steel which willconstitute the cutting blade 10 is first pierced or punched to forminitial clearance holes or slots 16. This operation may be carried outconveniently by means of a punch press of conventional design, the metalat the hole or slot portions being completely severed from the blade.The size and shape of the openings 16 may be varied according to theintended purpose of the tool and the final design desired. For optimumresults, it is preferred that the openings 16 be rectangular in shape,as best shown in FIG. 1 of the drawing. The holes 16 are preferably of asufiicient size to provide the desired chip clearance after the finaltooth form is produce-d while at the same time the size of the openingsis kept to a minimum for maximum strength of the blade. By way ofspecific example, in preparing a tool particularly adapted for filingwood, the openings 16 are preferably of the order of .15 to .20 inch inlength and approximately .06 to .08 inch in width. The number of holes16 and spacing thereof will depend upon the number and location of theteeth desired.

Following the punching operation of the metal strip, a portion of theblade rearwardly of each initial clearance hole 16 is fashioned byswaging into the initial stage of the tooth form, as illustrated in FIG.3.. The swaging operation may be carried out by a pair of dies 18, 20which operate against the blade areas rearwardly of each of therectangular initial clearance slots 16.

In order to more fully understand the invention, the unitary initialtooth form of the teeth 14, as shown in FIG. 3, may be considered topossess three contiguous portions; a root portion 22, a shank portion 24and a. tongue portion 26. The action of dies 18 and 20 against the bodyof the metal sheet rearwardly of the openings 16 causes the root portion22 of the tooth to be bent downwardly at an angle from the plane of themain body portion of the metal sheet. In the specific embodiment shownin the drawing, the angle is approximately 30 degrees, although this isnot critical and may be varied within reasonable limits. At the sametime, the shank portion 24 is depressed and offset downwardly from theupper surface 42 of the strip. This disposes the lower surface 28 of theshank portion 24 below the bottom surface 30 of the main body portion ofthe tool blade 10 to permit the subsequent grinding operation to bedescribed later. At the same time, the left-hand portion of the tooth,as viewed in the drawing, is deformed or cold-forged into the acutetongue portion 26 providing the initial breast or rake face 44 of thetooth. In this operation, the side edges 32 of the tooth are not severedfrom the main body portion of the tool, as best shown in FIG. 6, thusretaining maximum strength and support. At the same time the metal ofthe tongue portion 26 of the tooth is compacted and densified by theswaging operation causing a material increase in the strength thereof.

The swaging operation resulting in the forwardly projecting acute tongueportion 26 forms an initial rake face 44 and determines the includedangle A of the final tooth 14, which angle is, at the same time, relatedto the final forming step for determining the rake and clearance angleswhich may be applied to the tooth. It is an advantage of the inventionthat a tooth form having a greater included angle which provides astronger and more rugged tooth form will also permit a minimum finalrake angle and vice versa. Accordingly, when the tool is intended foruse with soft materials such as wood, the tooth portion may be given anincluded angle of the order of 30 degrees which provides a suflicientlyrugged tooth structure for this use while at the same time permitting arelatively large rake angle. On the other hand, if the tool is for useon relatively hard material, the included angle may be increased to asmuch as 80 degrees which greatly increases the tooth strength and at thesame time permits the formation of a rake angle of the order of O to 10degrees. In either case, the tooth strength is greater than in teeth ofcomparable dimensions made in a normal stamping operation due to thedensifying and compacting effected during the swaging operation.

Following the swaging operation, the initial tooth form undergoes agrinding operation so as to remove a minor amount, for example about.003", of that portion of the tooth which extends below the bottomsurface 30 of the tool blade 10. As shown in FIG. 4, the grinding is ina plane parallel to surface 30. The grinding serves to remove lowersurface 28 and to additionally remove any surface irregularities thatmay be present as a result of the prior operations, While at the sametime providing a sharp cutting edge 34. While the portions of the root,shank and tongue extending below surface 30 of tool blade 10 may becompletely removed, if desired, so long as the strength of the tooth isnot detrimentally affected thereby, it is an advantage of the inventionthat only a very small portion of the initial tooth form need beremoved, thus permitting the major portion of the sheet metal tocontribute to the strength of the structure and reduce the time and costinherent in an extensive grinding operation.

The final tooth form, as shown in FIG. 5, is obtained by bending orforming downwardly the forward end or lip 36 of tongue 26 containingcutting edge 34 so as to produce the final rake angle B and at the sametime produce a clearance angle C for the tooth. This operation may beaccomplished by subjecting the forward half of tongue portion 26 to apair of bending or forming dies 38, 40 which will cause the lip 36 oftongue 26 to bend outwardly from surface 30 of tool blade 10 and thusestablish the final rake and clearance angles as well as the bite ordistance between surface 30 and cutting edge 34. The final tooth formthus produced may then be hardened using conventional techniques and thedesired finish may be applied to the blade.

As mentioned hereinabove, the rake and clearance angles are interrelatedwith the included angle formed by the swaging operation and will varydepending upon the materials to be cut; for instance, wood, leather andmaterials of related hardness are best cut with tools having a rakeangle of 20-45 and a clearance angle of l20.

For cutting materials in the hardness range of soft steel or gray iron,it is desirable to use a rake of 0 to 15 degrees and a clearance angleof 10 to 15 degrees while materials of intermediate hardness such asplastics and soft metals require a rake of about 15 to 40 degrees and aclearance angle of 10 to 15 degrees.

As best shown in the sectional views of FIGS. 5 and 6, the tooth 14integrally depends from the body of tool blade 10 both at its rearwardportion through root 22 and along a substantial portion of its sides 32.That dependence in conjunction with the structural configuration of theteeth 14 imparts improved strength and durability to the cuttingelements and through the cutting elements to the tool. The configurationof the shank portion 24 which, as shown, is slightly offset from thebody of blade 10 gives the beneficial back up support and integrity fromadverse bending in the areas of juncture with the body of the blade.Further, it advantageously provides a sturdiness of structure along thecomponent of greatest force due to the offset location of the shankportion and the substantial retention of material within that portion.

In addition to the support provided by the back up portion of thecutting elements, the invention facilitates optimum adjustability amongthe interrelated included, rake and clearance angles while impartingadded durability to the leading portion of the cutting elements. Theswaging operation with its forwardly extruding coldflow of the metal andthe associated densification of the tongue portion not only impartsgreater strength to that portion of the cutting element but results inthe formaion of any desired included angle and its related rake andclearance angles. The relationship between the latter two angles islimited by the included angle formed during the swaging operation, butis, of course, finally determined by the forming operation which alsosets the bite or maximum depth of cut. Further, since the rate of biteor dig is also a function of the rake and clearance angles, the presentinvention provides the optimum adjustment for all of those relatedfactors. In addition, it enables the adjustment of those interdependentrelationships by means of simple and reliable operations at low costwhile increasing the quality of the product.

As will be apparent to persons skilled in the art, various modificationsand adaptations of the sructure above described will become readilyapparent without departure from the spirit and scope of the invention,the scope of which is defined in the appended claims.

I claim:

1. In a method of forming a cutting tool, the steps comprising punchinga plurality of openings in a metal sheet, swaging the portions of thesheet immediately rearwardly of the holes to provide an initial toothform having a root portion integrally joined to the metal sheet and bentdownwardly and forwardly at an acute angle thereto and a shank portionintegrally joined to and extending forwardly from the root portion at anangle thereto, and compacting and deforming said shank portion at itsforward end to form a forwardly projecting tapering tongue portion,grinding the lower surface of at least the tongue portion to form asharp cutting edge at the forward end of the tongue portion, andthereafter bending the tongue portion to project the cutting edge belowsaid lower surface thereby forming the desired rake and clearanceangles.

2. In a method of forming a cutting tool, the steps comprising punchinga plurality of openings in a metal sheet, swaging the portions of thesheet immediately rearwardly of the holes to provide an initial toothform comprising a root port-ion integrally joined to the metal sheet andbent downwardly and forwardly at an acute angle thereto and a shankportion integrally joined to and extending forwardly from the rootportion and having its upper surface disposed below the upper surface ofthe metal sheet, and compacting and deforming said shank portion at itsforward end to form a forwardly projecting tapered tongue portion,grinding the lower surface of at least the tongue portion to form asharp cutting edge at the forward end of the tongue portion, andthereafter bending the tongue portion downwardly to project the cuttingedge below said lower sunface thereby forming the desired rake andclearance angles.

3. In a method of forming "a cutting tool, the steps comprising punchinga plurality of rectangular holes in a metal sheet with the holesarranged in successive rows extending transversely of the cuttingdirection of the tool, swaging the portions of the metal sheetimmediately rearwatrdly of the holes to provide an initial tooth formhaving a root portion integrally joined at its side and rear edges withthe metal sheet and bent clown- Wardly and forwardly at an acute anglethereto and a shank portion integrally joined to and extending forwardlyfrom the root portion having its lower surface disposed below the lowersurface of the metal sheet and compacting and deforming said shankportion at its forward end to form a forwardly projecting taperingtongue, grinding the lower surface of at least the tongue portion toform a sharp cutting edge at the forward end of the tongue, andthereafter bending a port-ion of the tongue downwardly and rearwardly toproject the cutting edge below said lower surface thereby forming thedesired rake and clearance angles.

4. In a method of forming a cutting tool, the steps comprising punchinga plurality of rectangular holes in a metal sheet with the holesarranged in successive rows extending transversely of the cuttingdirection of the tool, swaging the portions of the sheet immediatelyrearwairdly of the holes to provide an initial tooth form comprising aroot portion integrally joined at its side and rear edges with the metalsheet and bent downwardly and forwardly at an acute angle thereto and ashank portion integrally joined to the root portion and extendingforwardly from the root portion with its lower surface disposed belowthe lower surface of the metal sheet, and compacting and deforming saidshank portion at its forward end to form a forwardly projecting taperedtongue portion having a lower surface contiguous with the lower surfaceof the shank portion, grinding the lower surface of the shank and tongueportion to form a sharp cutting edge at the forward end of the tongueportion, and thereafter bending the tongue portion downwardly rearwardlyof the cutting edge to project the cutting edge below said lower surfacethereby forming the desired rake and clearance angles.

References Cited by the Examiner UNITED STATES PATENTS 2,678,571 5/1954Booth 76-101 2,976,747 3/ 1961 Schatzschock 76101 2,984,892 5/1961Oxford 2978 3,016,600 1/1962 Schatzschock 29--78 GRANVILLE Y. CUSTE'R,JR. Primary Examiner.

WILLIAM W. DYER, Examiner.

H. HINSON, Assistant Examiner;

1. IN A METHOD OF FORMING A CUTTING TOOL, THE STEPS COMPRISING PUNCHINGA PLURALITY OF OPENINGS IN A METAL SHEET, SWAGING THE PORTIONS OF THESHEET IMMEDIATELY REARWARDLY OF THE HOLES TO PROVIDE AN INITIAL TOOTHFORM HAVING A ROOT PORTION INTEGRALLY JOINED TO THE METAL SHEET AND BENTDOWNWARDLY AND FORWARDLY AT AN ACUTE ANGLE THERETO AND A SHANK PORTIONINTEGRALLY JOINED TO AND EXTENDING FORWARDLY FROM THE ROOT PORTION AT ANANGLE THERETO, AND COMPACTING AND DEFORMING SAID SHANK PORTION AT ITSFORWARD END TO FORM A FORWARDLY PROJECTING TAPERING TONGUE PORTION,GRINDING THE LOWER SURFACE OF AT LEAST THE TONGUE PORTION TO FORM ASHARP CUTTING EDGE AT THE FORWARD END OF THE TONGUE PORTION, ANDTHEREAFTER BENDING THE TONGUE PORTION TO PROJECT THE CUTTING EDGE BELOWSAID LOWER SURFACE THEREBY FORMING THE DESIRED RAKE AND CLEARANCEANGLES.